1. Field of the Invention
The present invention relates to an organic electroluminescence(EL) display panel, and more particularly to an organic EL display panel and a method for sealing the same.
2. Description of the Related Art
Recently, with a large sized tendency of a display device, request for a flat display occupied in a small space is increasing. As an example of the flat display, an EL display is receiving much attention.
The EL display is divided into an inorganic EL display and an organic EL display in accordance with its materials. Of them, the organic EL display emits light while electrons injected into an organic EL layer are combined with a hole and erased. The organic EL layer is formed between a cathode and an anode.
The organic EL display has an advantage in that it is driven at a lower voltage (for example, about 10V or less) than a voltage of a plasma display panel (PDP) or an inorganic EL display. Also, since the organic EL display has further advantages such as a wide viewing angle, high speed reactivity, and high contrast, it is used as a pixel of a graphic display, a television video display, and a surface light source. Moreover, since the organic EL display is thin and weighs light, and its color sensitivity is good, it is suitable for a next generation flat display.
However, the most serious problem in commercially using the organic EL display is that its life span is short.
The life span of the display is determined by various factors such as impurities within organic matters, interface between the organic matters and electrodes, a low crystallization temperature (Tg) of the organic matters, and oxidation of the display due to oxygen and humidity. Problems related to such factors can be solved by refinement of the organic matters, development of a material having a high crystallization temperature, and induction of an organic metal to the interface between the electrodes and the organic matters. However, it is difficult to solve the problem related to oxidation of the display due to oxygen and humidity.
Oxygen and humidity that oxidize the display may exist in the display or may externally be permeated during the fabricating process steps. Oxygen and humidity are permeated into a pinhole of the display and oxidize an organic film and metal, thereby failing to perform a light emitting function of the display.
In the related art, to solve this problem, the display is covered with a shield glass to externally cut off humidity and oxygen.
In other words, as shown in FIGS. 1a and 1b, an organic EL display provided with a glass panel 1, a first electrode 2, an organic EL layer 3, and a second electrode 4 is covered with a shied glass 5 to cut off humidity and oxygen.
The shield glass 5 is attached to a corner portion of the panel by an adhesive 6.
However, since adhesive strength of the adhesive 6 is not good for a glass panel, the adhesive 6 is detached from the panel after a constant time elapses.
If the adhesive 6 is detached from the panel, a gap occurs between the panel and the adhesive so that humidity or oxygen is permeated into the display. For this reason, a problem arises in that life span of the display is shortened.
To solve the above problems, an object of the present invention is to provide an organic EL display panel and a method for sealing the same, in which life span of the display can be improved by adhesive strength between a panel and an adhesive.
To achieve the above object, in an organic EL display panel having a multi-layered structure in which a first electrode and a second electrode are formed on a transparent panel and at least one organic EL layer is formed between them, the organic EL display panel according to the present invention includes a buffer layer formed on the transparent panel and a shield cover located on the buffer layer.
In another aspect, in a method for sealing an organic EL display panel having a multi-layered structure in which a first electrode and a second electrode are formed on a transparent panel and an organic EL layer is formed between the first and second electrodes, the method for sealing an organic EL display panel according to the present invention includes the steps of forming a buffer layer on the transparent panel, and locating a shield cover on the buffer layer.
The buffer layer is formed on an entire surface of the panel other than a tap bonding region and a pixel region of the first and second electrodes, or only on the panel of a region where the shield cover is located on the transparent panel, or both on the panel of a region where the shield cover is located and on the electrode of a region where the shield cover is located.
Also, the buffer layer of the region where the shield cover is located has an uneven shape or a dot shape. The dot shaped buffer layer is formed of any one of a round shape, a triangle shape, a quadrangle shape, a polygonal shape, and so on.
The buffer layer of the region where the shield cover is located and the buffer layer of a region other than the region where the shied cover is located have the same material as each other or a different material from each other. In other words, the buffer layer of the region where the shield cover is located includes a material of either silicon oxide or silicon nitride, while the buffer layer of the region other than the region where the shield cover is located includes a material of silicon oxide, silicon nitride, polyimide, or polyacryl.
In the present invention, an inorganic material such as silicon oxide and silicon nitride is formed on the panel of the region where the shield cover is located, so that adhesive strength between the panel and the adhesive is enhanced to prevent external humidity and oxygen from being permeated into the panel, thereby increasing life span of the display.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.